Referring to FIGS. 1 and 2, an existing tablet computer 7 includes a main body 71, a kickstand 72, and a hinge assembly 73 connecting the kickstand 72 to the main body 72. With the hinge assembly 73, the kickstand 72 is pivotal relative to the main body 71 to adjust an angle between the main body 71 and the kickstand 72 so that the tablet computer 7 may be placed on a desktop at a desired inclined position.
As shown in FIGS. 3 and 4, the hinge assembly 73 includes a first hinge unit 731, a second hinge unit 733, and a guiding unit 732. The first and second hinge units 731, 733 are slidably connected to each other by the guiding unit 732. The second hinge unit 733 is slidable relative to the guiding unit 732, and includes a hinge body 733b, a pivot shaft 733c and an eccentric extension member 733d. The hinge body 733b has an installing space 733a. The pivot shaft 733c is connected to the hinge body 773b and is disposed in the installing space 733a. The eccentric extension member 733d is eccentrically and rotatably sleeved on the pivot shaft 733c and has an end pivotally connected to the first hinge unit 731. Because the eccentric extension member 733d is eccentrically rotatable relative to the pivot shaft 733c, a torsional force is unevenly generated by the hinge assembly 73 for supporting the main body 71. With the use of the eccentric extension member 733d, when the angle between the kickstand 72 and the main body 71 is increased, application force required to operate the kickstand 72 is increased. However, because no clearance exists between the eccentric extension member 733d and the pivot shaft 733c, the friction torque created by the eccentric extension member 733d is unstable due to wear caused between the eccentric extension member 733d and the pivot shaft 733c. After the wear occurs for a long period, the application force required to operate the kickstand 72 becomes high and low irregularly.